Control-target vehicle setting apparatus, control-target vehicle setting system, and control-target vehicle setting method

ABSTRACT

A control-target vehicle setting apparatus sets a control-target vehicle that serves as a target for driving assistance control. The control-target vehicle setting apparatus includes a detection signal acquiring unit and a setting control unit. The detection signal acquiring unit acquires a first detection signal that indicates a target by an image and a second detection signal that indicates a target by a reflection point. The setting control unit sets an acquired forward target as the control-target vehicle when the forward target is associated with an integration history that indicates that the forward target has been determined to be a vehicle using the first detection signal and the second detection signal in an integrated manner, even when the forward target is not associated with a movement history that indicates that the forward target has been detected as being a moving object.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of priority fromearlier Japanese Patent Application No. 2017-187657, filed Sep. 28,2017, the description of which is incorporated herein by reference.

BACKGROUND Technical Field

The present disclosure relates to a technology for setting acontrol-target vehicle that serves as a target for driving assistancecontrol of an own vehicle.

Related Art

A vehicle driving assistance apparatus has been proposed (for example,refer to JP-A-2005-145396). The vehicle driving assistance apparatusperforms driving assistance to enable an own vehicle (to which thevehicle driving apparatus is mounted) to follow a preceding vehicle (setas a control-target vehicle being a target for driving assistancecontrol of an one vehicle) using both an imaging unit and a radar unit.

However, in cases in which a stationary object of which movement has notbeen detected since the start of execution of driving assistance is setas a target for driving assistance control, an issue arises in thatdifferentiation between a stationary vehicle that is stopped and astationary object other than a vehicle that is present on a travel locus(trajectory) on which an own vehicle is driving is difficult.

Here, for example, a stationary object other than a vehicle includesstationary objects on a driving road such as a manhole in a road, andupper objects (overhead objects or high objects) such as signs andmarkers positioned above the travel locus. In addition, an issue alsoarises in that, when accuracy of the differentiation between astationary vehicle and a stationary object other than a vehicle is low,driving assistance cannot be appropriately performed.

SUMMARY

It is thus desired to provide a technology for enabling accuratedifferentiation between a stationary vehicle and a stationary objectother than a vehicle, and appropriate setting of a control-targetvehicle that serves as a target for driving assistance control performedin an own vehicle.

The present disclosure may be implemented by the following exemplaryembodiments.

A first exemplary embodiment provides a control-target vehicle settingapparatus that sets a control-target vehicle that serves as a target fordriving assistance control. The control-target vehicle setting apparatusincludes: a detection signal acquiring unit that acquires a firstdetection signal that indicates a target by an image and a seconddetection signal that indicates a target by a reflection point; and asetting control unit that sets a forward target as the control-targetvehicle when the forward target is associated with an integrationhistory that indicates that the forward target has been determined to bea vehicle using the first detection signal and the second detectionsignal in an integrated manner, even when the forward target is notassociated with a movement history that indicates that the forwardtarget has been detected as being a moving object.

As a result of the control-target vehicle setting apparatus of the firstexemplary embodiment, a stationary vehicle and a stationary object otherthan a vehicle can be accurately differentiated, and the control-targetvehicle can be appropriately set.

A second exemplary embodiment provides a control-target vehicle settingmethod for setting a control-target vehicle that is a target of drivingassistance control. The control-target vehicle setting method includes:acquiring a first detection signal that indicates a target by an imageand a second detection signal that indicates a target by a reflectionpoint; and setting a forward target as the control-target vehicle whenthe forward target is associated with an integration history thatindicates that the forward target has been determined to be a vehicleusing the first detection signal and the second detection signal in anintegrated manner, even when the forward target is not associated with amovement history that indicates that the forward target has beendetected as being a moving object.

As a result of the control-target vehicle setting method of the secondexemplary embodiment, a stationary vehicle and a stationary object otherthan a vehicle can be accurately differentiated, and the control-targetvehicle can be appropriately set. The present disclosure may also beimplemented as a control-target vehicle setting program or acomputer-readable recording medium on which the program is recorded.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an explanatory diagram of a vehicle to which a control-targetvehicle setting apparatus according to a first embodiment is mounted;

FIG. 2 is a block diagram of a functional configuration of a controlapparatus included in the control-target vehicle setting apparatusaccording to the first embodiment:

FIG. 3 is a flowchart of a processing flow of a control-target vehiclesetting process and a driving assistance control process performed bythe control-target vehicle setting apparatus according to the firstembodiment;

FIG. 4 is a flowchart of a processing flow of the control-target vehiclesetting process according to the first embodiment;

FIG. 5 is an explanatory diagram of a relationship between an ownvehicle and a stationary object on a driving road;

FIG. 6 is a flowchart of a processing flow of a control-target vehiclesetting process according to a second embodiment;

FIG. 7 is an explanatory diagram of a relationship between the ownvehicle and another vehicle serving as a forward target;

FIG. 8 is an explanatory diagram of a relationship between the ownvehicle and an upper object serving as a forward target;

FIG. 9 is an explanatory diagram of a relationship between distance andabsolute speed difference between a forward target and the own vehicle:

FIG. 10 is a flowchart of a processing flow of a control-target vehiclesetting process according to a third embodiment; and

FIG. 11 is a flowchart of a processing flow of a control-target vehiclesetting process according to a fourth embodiment.

DESCRIPTION OF THE EMBODIMENTS

A control-target vehicle setting apparatus, a control-target vehiclesetting system, and a control-target vehicle setting method according toseveral embodiments of the present disclosure will hereinafter bedescribed.

First Embodiment

As shown in FIG. 1, a control-target vehicle setting apparatus 10according to a first embodiment is used so as to be mounted to a vehicle500. The control-target vehicle setting apparatus 10 is merely requiredto include at least a control apparatus 100. A control-target vehiclesetting system includes, in addition to the control-target vehiclesetting apparatus 10, a radar electronic control unit (ECU) 21, a cameraECU 22, a yaw rate sensor 23, a wheel speed sensor 24, a throttledriving apparatus 31, and a brake assistance apparatus 32. The vehicle500 includes an internal combustion engine (ICE), wheels 501, a brakeapparatus 502, a brake line 503, a front windshield 510, and a frontbumper 520.

The radar ECU 21 is connected to a millimeter-wave radar 211 that emitsradio waves and detects reflected waves from a target (object). Theradar ECU 21 generates a detection signal that indicates a target by areflection point using the reflected wave acquired by themillimeter-wave radar 21. The radar ECU 21 then outputs the detectionsignal. The camera ECU 22 is connected to a front camera 221. The cameraECU 22 generates a detection signal that indicates a target by an imageusing an image acquired by the front camera 221 and shape patterns oftargets that are prepared in advance. The camera ECU 22 then outputs thedetection signal. Each of the radar ECU 21 and the camera ECU 22 is amicroprocessor that includes a calculating unit, a storing unit, and aninput/output unit.

The radar ECU 21 and the millimeter-wave radar 211 correspond to a firstdetecting unit. The camera ECU 22 and the front camera 221 correspond toa second detecting unit. In addition to the millimeter-wave radar 211, alaser radar (LIDAR) or an ultrasonic wave detector may be used as adetector that detects the reflected waves. The ultrasonic wave detectoremits sound waves and detects the reflected waves of the sound waves. Inaddition to the front camera 221, a stereo camera or a multi-camera(multiple cameras) may be used as an imaging apparatus that captures animage of the target. The stereo camera is composed of two or morecameras.

In the vehicle 500, the internal combustion engine ICE is provided withthe throttle driving apparatus 31. The throttle driving apparatus 31drives a throttle valve that adjusts the amount of intake air andcontrols output of the internal combustion engine ICE. In the vehicle500, each wheel 501 is provided with the brake apparatus 502.

The brake apparatus 502 implements braking of the corresponding wheel501 through hydraulic pressure of a brake fluid that is supplied throughthe brake line 503 based on operation of a brake pedal by a driver. Thebrake line 503 includes a brake piston and a brake fluid line. The brakepiston generates hydraulic pressure of the brake fluid based on thebrake pedal operation. According to the present embodiment, the brakeassistance apparatus 32 is provided on the brake line 503. The brakeassistance apparatus 32 performs hydraulic control independent of thebrake pedal operation and thereby implements brake assistance.

A configuration in which a control signal line is provided instead ofthe brake fluid line and an actuator that is provided for each brakeapparatus 502 is operated may be used as the brake line 503. As a resultof the throttle driving apparatus 31 and the brake assistance apparatus32, a constant-speed driving and inter-vehicle distance control process,that is, adaptive cruise control (ACC) is implemented as drivingassistance control. In the constant-speed driving and inter-vehicledistance control process, an own vehicle (to which control-targetvehicle setting apparatus 10 is mounted) is controlled so as to drive ata preset vehicle speed while maintaining an inter-vehicle distancebetween a preceding vehicle and the own vehicle at a fixed distance.

In addition to the constant-speed driving and inter-vehicle distancecontrol process, driving assistance includes steering assistance inwhich steering control of a steering mechanism is performed independentof operation of a steering wheel by the driver. The steering mechanismincludes the steering wheel and a steering rod (not shown). Suchoperations may be controlled by a driving assistance apparatus thatincorporates the functions of the brake assistance apparatus.

As shown in FIG. 2, the control apparatus 100 includes a centralprocessing unit (CPU) 101, a memory 102, an input/output interface 103,and a bus 104. The CPU 101, the memory 102, and the input/outputinterface 103 are connected by the bus 104 so as to be capable oftwo-way communication.

The memory 102 includes a memory, such as a read-only memory (ROM), thatnon-volatilely stores a control-target vehicle setting program P1 and adriving assistance control program P2 in a read-only manner. Thecontrol-target vehicle setting program P1 is used to set acontrol-target vehicle (target preceding vehicle) that is a target fordriving assistance control of the own vehicle. The driving assistancecontrol program P2 is used to perform the driving assistance control.The memory 102 also includes a memory, such as a random access memory(RAM), that is readable and writable by the CPU 101. Furthermore, thememory 102 may also store therein a flag that indicates whether or not amovement history is present and a flag that indicates whether or not afusion (FSN) history is present. The flags will be described hereafter.

The CPU 101 functions as a setting control unit by opening thecontrol-target vehicle setting program P1 stored in the memory 102 in aread-write memory and running the program. In a similar manner, the CPU101 functions as a driving assistance control unit by running thedriving assistance control program P2. The CPU 101 may be a single CPU.Alternatively, the CPU 101 may be a plurality of CPUs that each run aprogram. Still alternatively, the CPU 101 may be a multi-thread CPU thatsimultaneously runs a plurality of programs.

The radar ECU 21, the camera ECU 22, the yaw rate sensor 23, the wheelspeed sensors 24, the throttle driving apparatus 31, and the brakeassistance apparatus 32 are each connected to the input/output interface103 by a control signal line.

The detection signals are inputted from the radar ECU 21, the camera ECU22, the yaw rate sensor 23, and the wheel speed sensors 24. A controlsignal that designates a throttle valve opening is outputted to thethrottle driving apparatus 31. A control signal that designates a brakelevel is outputted to the brake assistance apparatus 32. Theinput/output interface 103 may be referred to as a detection signalacquiring unit that acquires a first detection signal and a seconddetection signal.

The millimeter-wave radar 211 is a sensor that detects a distance to atarget, as well as a relative speed and an angle of the target, byemitting millimeter waves and receiving reflected waves reflected by thetarget. According to the present embodiment, the millimeter-wave radar211 is arranged in each of a center portion and both side surfaces ofthe front bumper 520.

An unprocessed detection signal that is outputted from themillimeter-wave radar 211 is processed by the radar ECU 21 and inputtedto the control apparatus 100 as the first detection signal. The firstdetection signal is composed of a point that indicates a singlerepresentative position of the target or a series of points thatindicate a plurality of representative positions of the target.Alternatively, the radar ECU 21 may not be provided. In this case, asignal indicating an unprocessed reception wave is inputted to thecontrol apparatus 100 from the millimeter-wave radar 211 as the firstdetection signal. In cases in which the unprocessed reception wave isused as the detection signal, the control apparatus 100 performs signalprocessing to identify the position and the distance of the target.

The front camera 221 is an imaging apparatus that includes a singleimage sensor, such as a charge-coupled device (CCD) image sensor. Thefront camera 221 is a sensor that outputs outer-shape information of atarget as image data that serves a detection result by receiving visiblelight.

The camera ECU 22 performs a feature-point extraction process on theimage data outputted from the front camera 221. The camera ECU 22performs a comparison between a pattern formed by extracted featurepoints and a comparison pattern that indicates an outer shape of atarget to be set as a target for driving assistance control, that is, avehicle. The comparison pattern is prepared in advance. When theextracted pattern and the comparison pattern match or are similar, thecamera ECU 22 generates a frame image that includes the determinedtarget. Meanwhile, when the extracted pattern and the comparison patterndo not match or are not similar, that is, when the extracted pattern andthe comparison pattern are dissimilar, the camera ECU 22 does notgenerate a frame image.

When a plurality of targets are included in the image data, the cameraECU 22 generates a plurality of frame images that each include adetermined target. The frame images are then inputted to the controlapparatus 100 as the second detection signal. Each frame image isexpressed by pixel data and includes positional information, that is,coordinate information of the determined target.

The number of frame images that can be included in the detection signaldepends on a bandwidth between the camera ECU 22 and the controlapparatus 100. The camera ECU 22 may not be separately provided.Unprocessed image data picked up by the front camera 221 may be inputtedto the control apparatus 100 as the second detection signal. In thiscase, the control apparatus 100 may perform determination of the targetusing the outer-shape pattern of the target.

According to the present embodiment, the front camera 22 is arranged inan upper center portion of the front windshield 510. The pixel dataoutputted from the front camera 22 is monochromatic pixel data or colorpixel data. When a target other than a vehicle is desired as the targetto be set as the control target, an outer-shape pattern for the desiredtarget may be prepared. The camera ECU 22 may then output a frame imagethat includes the desired target as the detection signal. In this case,in a process performed by the control apparatus 100 at a later stage,the frame image appropriate for the process may be selectively used.

The yaw rate sensor 23 is a sensor that detects a rotation anglevelocity of the vehicle 500. For example, the yaw rate sensor 23 isarranged in a center portion of the vehicle 500. The detection signaloutputted from the yaw rate sensor 23 is a voltage value that isproportional to a rotation direction and an angular velocity.

The wheel speed sensor 24 is a sensor that detects a rotation speed ofthe wheel 501. The wheel speed sensor 24 is provided for each wheel 501.An output signal outputted from the wheel speed sensor 24 is a voltagevalue that is proportional to the wheel speed or a pulse wave of whichthe interval is based on the wheel speed. As a result of the detectionsignal from the wheel speed sensor 24 being used, information such as avehicle speed of the own vehicle and a traveling distance of the ownvehicle can be acquired.

The throttle driving apparatus 31 is an actuator that adjusts an openingof the throttle valve based on operation of an accelerator pedal by thedriver or regardless of the operation of the accelerator pedal by thedriver, and controls the output of the internal combustion engine ICE.For example, the throttle driving apparatus 31 is a stepper motor. Adriver that controls the operation of the actuator based on a controlsignal from the CPU 101 is mounted in the throttle driving apparatus 31.According to the present embodiment, the throttle driving apparatus 31is provided in an intake manifold. The throttle driving apparatus 31increases and decreases the amount of air drawn into the internalcombustion engine ICE based on the control signal from the controlapparatus 100.

The brake assistance apparatus 32 is an actuator that implements brakingby the brake apparatus 502 regardless of the operation of the brakepedal by the driver. A driver that controls the operation of theactuator based on a control signal from the CPU 101 is mounted in thebrake assistance apparatus 32. According to the present embodiment, thebrake assistance apparatus 32 is provided on the brake line 503. Thebrake assistance apparatus 32 increases and decreases hydraulic pressurein the brake line 503 based on the control signal from the controlapparatus 100. For example, the brake assistance apparatus 32 iscomposed of a module that includes an electric motor and a hydraulicpiston that is driven by the electric motor. Alternatively, a brakecontrol actuator that is already incorporated as a lateral-slidingprevention apparatus or an anti-lock brake system may be used.

A control-target vehicle setting process and a driving assistancecontrol process performed by the control-target vehicle settingapparatus 10 according to the first embodiment will be described.

For example, a processing routine shown in FIG. 3 is repeatedlyperformed at a predetermined time interval from when the control systemof the vehicle is started until the control system is stopped, or fromwhen a start switch is turned on until the start switch is turned off. Acontrol-target vehicle setting process (step S10) is performed by theCPU 101 running the control-target vehicle setting program P1. A drivingassistance control process (step S20) is performed by the CPU 101running the driving assistance control program P2.

In FIG. 3, the control-target vehicle setting process (step S10) and thedriving assistance control process (step S20) are included in a sameprocessing flow to facilitate description. However, the control-targetvehicle setting process (step S10) and the driving assistance controlprocess (step S20) can be independently performed at differing timings.

For example, the driving assistance control process (step S20) includesthe constant-speed driving and inter-vehicle distance control process, abrake assistance process, and a steering assistance process. The brakeassistance process includes sudden braking and gradual braking toprevent collision with the control-target vehicle. The steeringassistance process includes steering to prevent collision with thecontrol-target vehicle and steering to prevent deviation from a trafficlane.

Details of the control-target vehicle setting process (step S10)according to the first embodiment will be described with reference toFIG. 4 and FIG. 5. The flowchart shown in FIG. 4 is repeatedly performedat a predetermined time interval.

As shown in FIG. 4, the CPU 101 acquires attribute information(forward-target information) of a forward target (target ahead) usingthe radar ECU 21 and the camera ECU 22 (step S100). The attributeinformation includes the relative speed, reflected-power strength,position coordinates, and direction of the forward target. The forwardtarget is a target to be subjected to determination and therefore may bereferred to as a determination target.

The CPU 101 determines whether or not the target detected by themillimeter-wave radar 211 has moved, every time the information on theforward target is acquired. The CPU 101 associates the detected targetwith a movement history that indicates whether or not the target hasmoved.

Specifically, after the start of an initial execution of the presentprocessing routine, the CPU 101 determines whether or not a target thathas been initially detected by the millimeter-wave radar 211 has movedbased on whether or not the relative speed or the position coordinatesof the reflection point corresponding to the target has changed at eachacquisition timing.

For example, when determined that the target is moving, the CPU 101associates the target with a movement-history present flag thatindicates that the target is a moving object. When determined that thetarget is not moving, the CPU 101 associates the target with amovement-history absent flag that indicates that the target is astationary object.

Furthermore, the CPU 101 performs a data fusion process that improvesdetermination accuracy regarding whether or not the target is a vehicleusing the detection signal inputted from the radar ECU 21 and thedetection signal inputted from the camera ECU 22. That is, the CPU 101performs a data integration process or combining process.

Specifically, the CPU 101 performs integration when the positioncoordinates of each reflection point indicating the target inputted fromthe radar ECU 21 correspond to the detection signal inputted from thecamera ECU 22, that is, the determined position coordinates of thevehicle included in the image frame. The CPU 101 associates the targetwith a fusion (FSN)-history present flag, that is, anintegration-history present flag that indicates that the target isdetermined to be a vehicle.

Meanwhile, when determined that a vehicle corresponding to the positioncoordinates of each reflection point indicating the target does notappear in the image frame and correspondence cannot be established, theCPU 101 associates the target with An FSN-history absent flag. Thetarget being associated with the FSN-history present flag means that thetarget is a stationary vehicle that is determined to be a vehiclethrough vehicle determination by pattern matching. The target beingassociated with the FSN-history absent flag means that the target is anundetermined stationary target of which the type of the target isunidentified.

A plurality of forward targets may be present. A plurality of targetsmay be included in the detection signals inputted from the radar ECU 21and the camera ECU 22. Therefore, the data fusion process is performedfor each target.

The detection of a target using the millimeter-wave radar 211 is noteasily affected by forward obstacles, the weather, and the like.Therefore, even when a target is detected by the millimeter-wave radar211, the detection of the target by the front camera 211 may not bepossible. In such cases, the data fusion process cannot be performed.The movement history flag and the FSN history flag are initialized, thatis, reset to indicate movement-history absent and FSN-history absentevery time the system in the vehicle 500 is started.

The CPU 101 determines whether or not the forward target of which theinformation has been acquired at step S100 is associated with themovement-history present flag (step S110). When determined that theforward target is associated with the movement-history present flag (Yesat S110), the CPU 101 sets the forward target as the control-targetvehicle (step S130). The CPU 101 then ends the present processingroutine. The forward target that is set as the control-target vehicle isassociated with a mark that indicates that the target is thecontrol-target vehicle. This association is recorded in the memory 102.

When determined that the forward target is not associated with themovement-history present flag (No at step S110), the CPU 101 determineswhether or not the forward target is associated with the FSN-historypresent flag (step S120). When determined that the forward target isassociated with the FSN-history present flag (Yes at step S120), the CPU101 sets the forward target as the control-target vehicle (step S130).The CPU 101 then ends the present processing routine.

When determined that the forward target is not associated with theFSN-history present flag (No at step S120), the CPU 101 does not set theforward target as the control-target vehicle (step S140). The CPU 101then ends the present processing routine.

In the example shown in FIG. 5, stationary targets that are notvehicles, such as a sign or marker that is an upper object (an overheadobject or a high object) St1 present above a driving road (i.e., atravel locus) on which an own vehicle M0 is driving and a manhole thatis an on-road stationary object St2 are not determined to be vehicleseven in the pattern matching process performed on the captured imagedata by the camera ECU 22.

Therefore, the camera ECU 22 does not output the image frames includingthese stationary targets as the detection signal. The CPU 101 cannotperform the data fusion process. As a result, these stationary targetsare not associated with the FSN-history present flag and are not set asthe control-target vehicle.

As a result of the control-target vehicle setting apparatus 10 accordingto the first embodiment, even a target that has no movement history,that is, a stationary object can be determined to be a vehicle throughpattern matching using the image data picked up by the front camera 221.In cases in which the target is associated with the FSN-history presentflag, the target can be determined to be a stationary vehicle and set asthe control-target vehicle.

Therefore, a stationary vehicle and a stationary forward target that isother than a vehicle can be accurately differentiated. Thecontrol-target vehicle can be appropriately set. That is, a stationaryvehicle that is conventionally difficult to differentiate from an upperobject or an on-road stationary object present on the travel locus canbe set as the control-target vehicle. As a result, the drivingassistance control can be performed under more conditions. The accuracyof driving assistance can be improved.

According to the first embodiment, the process for setting thecontrol-target vehicle at step S130 more specifically includes a step ofdetermining a plurality of control-target vehicle candidates and a stepof setting a single control-target vehicle candidate among the pluralityof control-target vehicle candidates as the control-target vehicle. Thatis, when a plurality of forward targets are present and the plurality offorward targets have the movement history or the FSN history, aplurality of control-target vehicle candidates may be determined.

For example, the setting of a single control-target vehicle is performedunder a condition that the control-target vehicle candidate is closestin distance to the own vehicle and has the highest relative speed inrelation to the own vehicle, among the plurality of control-targetvehicle candidates. The forward target that is the set control-targetvehicle candidate is associated with a mark that indicates that theforward target is the control-target vehicle. This processing detail canbe similarly applied to embodiments described below.

Second Embodiment

A control-target vehicle setting process according to a secondembodiment that is performed by the control-target vehicle settingapparatus 10 will be described with reference to FIG. 6 to FIG. 9.

The configurations of the vehicle 500, the control-target vehiclesetting apparatus 10, and the control-target vehicle setting system aresimilar to the configurations according to the first embodiment.Therefore, the configurations are given the same reference numbers.Descriptions thereof are omitted. In addition, processing steps similarto those of the control-target vehicle setting process according to thefirst embodiment are given the same step numbers. Descriptions thereofare omitted. The process in the flowchart shown in FIG. 6 is alsorepeatedly performed at a predetermined time interval.

The CPU 101 performs step S100 and step S110. According to the secondembodiment, at step S100, the CPU 101 performs an oncoming-vehicledetermination process and an upper-object determination process. Forexample, in the oncoming-vehicle determination process, the CPU 101 candetermine that the forward target is a moving vehicle that is advancingin a direction opposite the direction of the own vehicle using relativespeed. When the distance in a lateral direction between the forwardtarget and the own vehicle is greater than a distance prescribed inadvance, the CPU 101 can determine that the forward target is anoncoming vehicle. When determined that the forward target is an oncomingvehicle, the CPU 101 associates the forward target with anoncoming-vehicle-history present flag that indicates that the forwardtarget is determined to be an oncoming vehicle.

For example, in the upper-object determination process, the CPU 101 candetermine whether or not the forward target is an upper object based onthe distance and the relative speed between the upper object that is theforward target and the own vehicle.

As shown in FIG. 7, a relationship Vr=−Vn is established between arelative distance Vr of a forward target MI that is present at adistance d in a horizontal direction on the travel locus on which theown vehicle M0 is driving and a speed Vn of the own vehicle M0. When|Vr|=Vn, the forward target is a stationary object. When |Vr|>Vn, theforward target is an oncoming object (opposing object). When |Vr|<Vn,the forward target is a separating object that is moving away from theown vehicle.

Meanwhile, as shown in FIG. 8, a relationship Vr=−Vn×cos θ isestablished between the relative speed Vr of the upper object St1serving as the forward target that is present at a distance d obliquelyabove the driving road locus of the own vehicle M0 and the speed Vn ofthe own vehicle M0. Here, θ denotes an elevation angle. Therefore,compared to cases in which the forward target is a target that is presetin the horizontal direction, an absolute speed difference ofVerr=Vn×(1−cos θ) is present.

As shown in FIG. 9, the absolute speed difference Verr increases when 0increases, that is, when the height of the upper object St1 increasesand when the distance d between the own vehicle M0 and the upper objectSt1 decreases.

In FIG. 9, the height of the upper object St1 corresponding to acharacteristics line L1 is higher than the height of the upper objectSt1 corresponding to a characteristics line L2. When the distance dbetween the upper object St1 and the own vehicle M0 decreases, the upperobject St1 falls outside of the elevation angle of the millimeter-waveradar 211. Therefore, the absolute speed difference Verr becomes 0 km/hfrom a certain distance. As a result, a forward target of which theabsolute speed difference Verr increases as the distance d to the ownvehicle M0 decreases can be determined to be an upper object.

When determined that the forward target is an upper object, the CPU 101associates the forward target with an upper object determination flagthat indicates that the forward target is determined to be an upperobject. The upper-object determination flag is updated every time thedetermination regarding the upper object is performed.

When the relative speed between the forward target and the own vehicleM0 increases after the forward target is determined to be an upperobject, the CPU 101 may determine that the forward target is not anupper object. For example, the reflected wave from an upper end of afreight vehicle that has a high vehicle height and is driving at a lowspeed may be detected as a reflected wave from an upper object. In thiscase, the forward target is preferably set as the control-targetvehicle.

In the upper-object determination process, in addition to or instead ofthe distance and the relative speed between the upper object that is theforward target and the own vehicle, reflected power or an amount ofchange in reflected power may be used to determine whether or not theforward target is an upper object.

Compared to when the forward target is positioned ahead in thehorizontal direction, when the forward target is an upper object, thereflected power decreases as the distance between the forward target andthe own vehicle decreases. Therefore, whether or not the forward targetis an upper object can be determine based on the power of the reflectedwave becoming equal to or less than a reference value, or the reflectedpower changing in a decreasing manner.

Furthermore, in addition to or instead of the determination using themillimeter-wave radar 211, a determination by pattern matching may beperformed using the image data picked up by the front camera 221 andpreparing a comparison pattern for the upper object St1. For example,this process can be implemented by a rectangular pattern positionedahead and above being prepared as the comparison pattern.

In general, when the distance d between the upper object St1 that is theforward target and the own vehicle M0 is long, that is, the elevationangle θ is small, the upper object tends to be recognized as the forwardtarget that is present in the horizontal direction of the own vehicleM0. Therefore, in cases in which the millimeter-wave radar 211 is used,as well as in cases in which the front camera 221 is used, the forwardtarget is often determined to be an upper object at a timing at whichthe distance d between the upper object St1 and the own vehicle M0shortens.

Returning to the description regarding FIG. 6, when determined that theforward target of which the information has been acquired is associatedwith the movement-history present flag (Yes at step S110), the CPU 101determines whether or not the forward target has the oncoming-vehiclehistory or is determined to be an upper object (step S112).

As described above, the relative speed |Vr| in relation to the ownvehicle speed Vn decreases as the distance between the upper object St1and the own vehicle M0 decreases, that is, the speed of the forwardtarget that is the upper object St1 increases. As a result, the forwardtarget may be erroneously determined to be a separating object.Therefore, even when the forward target is a moving object, accuracy ofthe determination result regarding whether the forward target is amoving object or a stationary object can be improved by taking intoconsideration whether or not the forward target has been determined tobe an upper object with the passage of time, that is, as the distancebetween the forward target and the own vehicle decreases.

When determined that the forward target has the oncoming-object historyor is determined to be an upper object (Yes at step S112), the CPU 101proceeds to step S140 and does not set the forward target as thecontrol-target vehicle. The CPU 101 then ends the present processingroutine. If an oncoming vehicle or an upper object is set as thecontrol-target vehicle, driving assistance control that is unnecessaryin terms of preventing collision and the like is performed. Executionfrequency of driving assistance increases and smooth driving of the ownvehicle is inhibited.

When determined that the forward target does not have theoncoming-vehicle history or is not determined to be an upper object (Noat step S112), the CPU 101 proceeds to step S130 and sets the forwardtarget as the control-target vehicle. The CPU 101 then ends the presentprocessing routine.

When determined that the forward target is not associated with themovement-history present flag (No at step S110), the CPU 101 proceeds tostep S120. When determined that the forward target is associated withthe FSN-history present flag (YES at step S120), the CPU 101 determineswhether or not the forward target is determined to be an upper object(step S122).

In cases in which the distance between the forward target and the ownvehicle is long, even when the forward target is an upper object, theforward target may be considered to be a vehicle and the data fusionprocess may be performed. The forward target may thereby be associatedwith the FSN-history present flag. Meanwhile, when the forward target isa true upper object, the forward target is determined to be an upperobject by the above-described method as the distance between the forwardtarget and the own vehicle decreases. The forward target is therebyassociated with the upper-object determination flag.

When determined that the forward target is not associated with theupper-object determination flag (No at step S122), the CPU 101 proceedsto step S130 and sets the forward target as the control-target vehicle.The CPU 101 then ends the present processing routine.

When determined that the forward target is associated with theupper-object determination flag (Yes at step S122), the CPU 101determines whether or not the data fusion process is being continued forthe forward target (step S124). When the forward target is a true upperobject, the accuracy of the pattern matching process improves as thedistance between the forward target and the own vehicle decreases. Anerroneous data fusion process tends to not be performed. However, whenthe forward target is not an upper object, that is, the forward targetis a stationary vehicle, the accuracy of the pattern matching processimproves as the distance between the target above and the own vehicledecreases. The fusion process tends to be performed.

Therefore, even when the forward target is determined to be an upperobject, when determined that the data fusion process is being continued(FSN continued) at the time of the determination at step S124 (Yes atstep S124), the CPU 101 determines that the forward target is astationary vehicle. The CPU 101 proceeds to step S130 and sets theforward target as the control-target vehicle. The CPU 101 then ends thepresent processing routine.

When determined that the data fusion process is not being continued (Noat step S124), the CPU 101 proceeds to step S140 and does not set theforward target as the control-target vehicle. The CPU 101 then ends thepresent processing routine.

As a result of the control-target vehicle setting apparatus 10 accordingto the second embodiment, even when the forward target has the movementhistory, the forward target is not set as the control-target vehiclewhen at least either of the forward target being an oncoming vehicle andthe forward target being determined to be an upper object isestablished. Therefore, the driving assistance control is not performedfor a forward target that is an oncoming vehicle or an upper object.Excessive execution of the driving assistance control can be suppressed.

As a result of the control-target vehicle setting apparatus 10 accordingto the second embodiment, even when the forward target has the FSNhistory, the forward target is not set as the control-target vehiclewhen the forward target is determined to be an upper object. Inaddition, even when the forward target is determined to be an upperobject, the forward target is set as the control-target vehicle when thedata fusion process is currently being continued.

Therefore, an upper object being set as the control-target vehicle andunnecessary driving assistance control being performed can be suppressedor prevented, even when the upper object is erroneously determined to bea stationary object and associated with the FSN-history present flagduring the data fusion process.

In addition, the forward target can be set as the control-target vehiclewhen the data fusion process is currently being performed even when thedistance between the forward target and the own vehicle shortens and theforward target is determined to be an upper object rather than astationary vehicle. The driving assistance control can be performed fora forward target that is highly likely to be a stationary vehicle.

Third Embodiment

A control-target vehicle setting process according to a third embodimentthat is performed by the control-target vehicle setting apparatus 10will be described with reference to FIG. 10.

The configurations of the vehicle 500, the control-target vehiclesetting apparatus 10, and the control-target vehicle setting system aresimilar to the configurations according to the first embodiment and thesecond embodiment. Therefore, the configurations are given the samereference numbers. Descriptions thereof are omitted. In addition,processing steps similar to those of the control-target vehicle settingprocess according to the second embodiment are given the same stepnumbers. Descriptions thereof are omitted. The flowchart shown in FIG.10 shows processing steps that may be additionally incorporated betweenstep S124 and step S140 according to the second embodiment.

The CPU 101 performs step S124 in the flowchart shown in FIG. 6. Whendetermined that the data fusion process is not being continued (No atstep S124), the CPU 101 determines whether or not the forward target hasa control-target-vehicle setting history that indicates that the forwardtarget has been set as the control-target vehicle for an amount of timeprescribed in advance or longer (step S125).

When the forward target has the FSN history and is determined to be anupper object, and the data fusion process is not being continued, theforward target should not be set as a target for driving assistancecontrol. Meanwhile, when the forward target has been set as thecontrol-target vehicle for a predetermined amount of time or longer, thebehavior of the own vehicle may change as a result of the setting of thecontrol-target vehicle being canceled.

In particular, when the distance between the forward target that is thecontrol-target vehicle and the own vehicle decreases, the front camera211 is no longer able to capture an image of the forward target. As aresult, the CPU 101 can no longer continue the data fusion process. Whenthe distance between the own vehicle and the control-target vehicle isshort, the likelihood of deceleration control being performed as thedriving assistance control is high. A sense of deceleration may be lostas a result of the deceleration control being canceled.

In addition, when ACC is performed as the driving assistance control,the own vehicle may accelerate. Therefore, when the forward target hasthe control-target-vehicle setting history, the forward target is set asthe control-target vehicle based on a condition, even when the datafusion process is not being continued.

When determined that the forward target does not have thecontrol-target-vehicle setting history (No at step S125), the CPU 101proceeds to step S140 and does not set the forward target as thecontrol-target vehicle. The CPU 101 then ends the present processingroutine.

When determined that the forward target has the control-target-vehiclesetting history (Yes at step S125), the CPU 101 determines whether ornot a distance D between the forward target and the own vehicle is lessthan a distance threshold Dr (step S126). For example, the distancethreshold Dr is a distance that allows no leeway for avoidance of apreceding vehicle through braking or steering by the driver. Whendetermined that the distance D is less than the distance threshold Dr(Yes at step S126), the CPU 101 proceeds to step S130 and sets theforward target as the control-target vehicle. The CPU 101 then ends thepresent processing routine.

When determined that distance D is not less than the distance thresholdDr (No at step S126), the CPU 101 determines whether or not atime-to-collision (TTC) regarding the forward target is less than adetermination threshold TTCr prescribed in advance. For example, thedetermination threshold TTCr prescribed in advance is an amount of timethat allows no leeway for avoidance of a preceding vehicle throughbraking or steering by the driver.

When determined that the TTC is less than the determination thresholdTTCr (Yes at step S127), the CPU 101 proceeds to step S130 and sets theforward target as the control-target vehicle. The CPU 101 then ends thepresent processing routine. When determined that the TTC is not lessthan the determination threshold TTCr (No at step S127), the CPU 101proceeds to step S140 and does not set the forward target as thecontrol-target vehicle. The CPU 101 then ends the present processingroutine.

The determination regarding whether or not the distance D between theforward target and the own vehicle is less than the distance thresholdDr and the determination regarding whether or not the TTC regarding theforward target is less than the determination threshold TTCr may becomprehensively performed at a single processing step.

As a result of the control-target vehicle setting apparatus 10 accordingto the third embodiment, even when the data fusion process for theforward target is not being continued, the forward target can be set asthe control-target vehicle based on the relationship between the forwardtarget and the own vehicle when the forward target has thecontrol-target-vehicle setting history.

More specifically, when at least either of the distance D between theforward target and the own vehicle being less than the distancethreshold Dr and the TTC regarding the forward target being less thanthe determination threshold TTCr is determined, the forward target isset as the control-target vehicle. When this condition is not met, theforward target is not set as the control-target vehicle.

Therefore, uncertainty and discomfort experienced by the driver inaccompaniment with the setting of the control-target vehicle beingcanceled and the driving assistance control based on the forward targetbeing canceled can be reduced or eliminated. Meanwhile, when the forwardtarget is that for which the data fusion process is not being continuedand does not have the control-target setting history, the forward targetcan be excluded from the setting of the control-target vehicle andunnecessary execution of the driving assistance control can besuppressed or prevented.

Fourth Embodiment

A driving assistance control process according to a fourth embodimentwill be described with reference to FIG. 11. The driving assistancecontrol process is a detailed example of the driving assistance controlprocess (step S20) shown in FIG. 3. A constant-speed driving andinter-vehicle distance control process (ACC) is performed. In addition,the driving assistance control process is performed by a control-targetvehicle setting system including the control-target vehicle settingapparatus 10.

The CPU 101 acquires information on the forward target (step S200). Theinformation on the forward target is so-called attribute information andis acquired through the radar ECU 21 and the camera ECU 22. The CPU 101determines whether or not the forward target is the control-targetvehicle using the acquired information (step S210). The control-targetvehicle is also referred to as a preceding vehicle. Whether or not theforward target is the control-target vehicle may be determined by themark that is associated with the forward target when the forward targetis set as the control-target vehicle in the above-describedcontrol-target vehicle setting process.

When determined that the forward target is the control-target vehicle(Yes at step S210), the CPU 101 performs the constant-speed driving andinter-vehicle distance control process (step S220). The CPU 101 thenends the present processing routine.

The constant-speed driving and inter-vehicle distance control process isimplemented by the CPU 101 that runs the driving assistance controlprogram P2 transmitting a throttle-opening command signal to thethrottle driving apparatus 31 to maintain a preset speed. In addition,the CPU 101 transmits a throttle-opening command signal to the throttledriving apparatus 31 to maintain an inter-vehicle distance set inadvance and transmits a brake command signal to the brake assistanceapparatus 32 to implement a required degree of deceleration. Inaddition, information indicating a driving state of the own vehicle thatis inputted from the yaw rate sensor 23 and the wheel speed sensors 24is also used.

When determined that the forward target is not the control-targetvehicle (No at step S210), the CPU 101 performs a control-targetexclusion process (step S230). The CPU 101 then ends the presentprocessing routine.

For example, cases in which the forward target is excluded as thecontrol-target vehicle includes cases in which the forward target thathas been set as the control-target vehicle is determined to be an upperobject and cases in which a control-target vehicle candidate that iscloser to the own vehicle appears. For example, the control-targetexclusion process includes a process in which deceleration is maintainedwhen the own vehicle is decelerating as a result of the drivingassistance control, and acceleration is suppressed when the own vehicleis accelerating.

As described above, the upper object may be determined to be aseparating object because the relative speed thereof decreases as thedistance to the own vehicle decreases. Therefore, when a farawaystationary vehicle starts to drive when approaching the own vehicle, thestationary vehicle may be erroneously recognized as being an upperobject. Therefore, the above-described control-target exclusion processis performed to prevent collision or contact with the forward targetthat is actually a vehicle.

These processes are implemented by the CPU 101 continuing transmissionof the brake command signal to the brake assistance apparatus 32, andtransmitting a throttle-opening retention signal or a signal thatinstructs reduction of the throttle opening to the throttle drivingapparatus 31. Alternatively, the control-target exclusion processincludes a process in which the driving assistance control is canceledand control is returned to the driver.

As a result of the driving assistance control process according to thefourth embodiment, the control-target exclusion process is performedwhen the forward target is excluded as the control-target vehicle.Therefore, collision and contact between the forward target that isexcluded as the control-target vehicle and the own vehicle can bereduced or prevented.

Other Embodiments

(1) According to the first embodiment to the third embodiment, tofacilitate description, the determination regarding whether the forwardtarget is a moving object, a stationary object, an oncoming vehicle, oran upper object is performed and the forward target is associated withhistory information corresponding to the determination, when theattribute information of the forward target is acquired in thecontrol-target vehicle setting process.

However, the process in which the type of the forward target isdetermined and the forward target is associated with the correspondinghistory information may be performed at a separate timing independent ofthe control-target vehicle setting process. In this case, at step S100in the control-target vehicle setting process, the CPU 101 may retrievethe associated history information from the memory 102 based on theacquired attribute information of the forward target and use the historyinformation at subsequent processing steps.

(2) According to the above-described embodiments, the setting controlunit and the driving assistance control unit are implemented bysoftware, as a result of the CPU 101 running the control-target vehiclesetting program P1 and the driving assistance control program P2.However, the setting control unit and the driving assistance controlunit may be implemented by hardware, through an integrated circuit or adiscrete circuit programmed in advance.

The present disclosure is described above according to embodiments andvariation examples. However, the above-described embodiments of theinvention serve to facilitate understanding of the present disclosureand do not limit the present disclosure. The present disclosure may bemodified and improved without departing from the spirit of the inventionand the scope of claims.

In addition, the present disclosure includes equivalents thereof. Forexample, technical features according to the embodiments and variationexamples that correspond to technical features according to aspectsdescribed in the summary of the invention may be substituted or combinedas appropriate to solve the above-described issues in part or in itsentirety, or to achieve the above-described effects in part or in itsentirety. In addition, the technical features may be eliminated asappropriate unless described as being a requisite in the presentspecification.

For example, when the control-target vehicle setting apparatus of thevehicle according to the above-described first exemplary embodiment isan application example 1, the following application examples 2 to 9 arealso possible.

Application Example 2

In a control-target vehicle setting apparatus that is the control-targetvehicle setting apparatus described in the application example 1, thesetting control unit does not set the forward target as thecontrol-target vehicle when the forward target is determined to be anupper object above the driving road that is present above a driving roadon which the own vehicle is driving after the forward target isdetermined to be a vehicle.

Application Example 3

In a control-target vehicle setting apparatus that is the control-targetvehicle setting apparatus described in the application example 2, thesetting control unit sets the forward target as the control-targetvehicle when detection of the forward target using the first detectionsignal and the second detection signal in an integrated manner iscontinued, even when the forward target is determined to be an upperobject above the driving road that is present above a driving road onwhich the own vehicle is driving.

Application Example 4

In a control-target vehicle setting apparatus that is the control-targetvehicle setting apparatus described in any one of the applicationexamples 1 to 3, the setting control unit sets the forward target as thecontrol-target vehicle when at least either of the distance between theforward target and the own vehicle being less than the distancethreshold and the time-to-collision regarding the forward target beingless than the determination threshold is determined when the forwardtarget is not associated with an integration history, detection of theforward target using the first detection signal and the second detectionsignal in an integrated manner is not continued, and the forward targetis associated with a control-target-vehicle setting history thatindicates that the forward target has been set as the control-targetvehicle.

Application Example 5

In a control-target vehicle setting apparatus that is the control-targetvehicle setting apparatus described in the application example 4, thesetting control unit does not set the forward target as thecontrol-target vehicle when the forward target does not have theintegration history, detection of the forward target using the firstdetection signal and the second detection signal in an integrated manneris not continued, and the forward target is not associated with thecontrol-target-vehicle setting history.

Application Example 6

In a control-target vehicle setting apparatus that is the control-targetvehicle setting apparatus described in any one of the applicationexamples 1 to 5, the setting control unit does not set the forwardtarget as the control-target vehicle when at least either of the forwardtarget being associated with an oncoming vehicle history that indicatesthat the forward target has been determined to be an oncoming vehicleand the forward target being determined to be an upper object on thedriving road is established, even when the forward target is associatedwith the movement history.

Application Example 7

A control-target vehicle setting system includes the control-targetvehicle setting apparatus in any one of the application examples 1 to 6,a first detecting unit that outputs the first detection signal, and asecond detecting unit that outputs the second detection signal.

Application Example 8

A control-target vehicle setting system that is the control-targetvehicle setting system in the application example 7 further includes adriving assistance control unit that performs a constant-speed drivingand inter-vehicle distance control process as the driving assistancecontrol based on the set control-target vehicle. The driving assistancecontrol unit maintains deceleration when the own vehicle isdecelerating, suppresses acceleration when the own vehicle isaccelerating, or cancels the constant-speed driving and inter-vehicledistance control process, when the control-target vehicle for which theconstant-speed driving and inter-vehicle distance control process isperformed is changed from the control-target vehicle to anon-control-target vehicle.

Application Example 9

A target preceding vehicle setting apparatus sets a target precedingvehicle (control-target vehicle) for driving assistance control of anown vehicle. The target preceding vehicle setting apparatus includes adetection signal acquiring unit and a setting control unit. Thedetection signal acquiring unit acquires a first detection signal thatindicates a forward object (target) by an image and a second detectionsignal that indicates the forward object by a reflection point. Thesetting control unit sets the forward object as the target precedingvehicle when the forward object has been determined to be a vehiclebased on the first detection signal and the second detection signal,even when the forward object is not associated with a movement history.

What is claimed is:
 1. A control-target vehicle setting apparatus forsetting a control-target vehicle that serves as a target for drivingassistance control, the control-target vehicle setting apparatuscomprising: a detection signal acquiring unit that acquires a firstdetection signal that indicates a target by an image and a seconddetection signal that indicates a target by a reflection point; and asetting control unit that sets an acquired forward target as thecontrol-target vehicle when the forward target is associated with anintegration history that indicates that the forward target has beendetermined to be a vehicle using the first detection signal and thesecond detection signal in an integrated manner, even when the forwardtarget is not associated with a movement history that indicates that theforward target has been detected as being a moving object.
 2. Thecontrol-target vehicle setting apparatus according to claim 1, wherein:the setting control unit does not set the forward target as thecontrol-target vehicle when the forward target is determined to be anupper object that is present above a driving road on which the ownvehicle is driving after the forward target is determined to be avehicle.
 3. The control-target vehicle setting apparatus according toclaim 2, wherein: the setting control unit sets the forward target asthe control-target vehicle when detection of the forward target usingthe first detection signal and the second detection signal in anintegrated manner is continued, even when the forward target isdetermined to be an upper object that is present above the driving roadon which the own vehicle is driving.
 4. The control-target vehiclesetting apparatus according to claim 1, wherein: the setting controlunit sets the forward target as the control-target vehicle when at leasteither of a distance between the forward target and an own vehicle beingless than a distance threshold and a time-to-collision regarding theforward target being less than a determination threshold is determinedwhen the forward target is not associated with the integration history,detection of the forward target using the first detection signal and thesecond detection signal in an integrated manner is not continued, andthe forward target is associated with a control-target-vehicle settinghistory that indicates that the forward target has been set as thecontrol-target vehicle.
 5. The control-target vehicle setting apparatusaccording to claim 2, wherein: the setting control unit sets the forwardtarget as the control-target vehicle when at least either of a distancebetween the forward target and an own vehicle being less than a distancethreshold and a time-to-collision regarding the forward target beingless than a determination threshold is determined when the forwardtarget is not associated with the integration history, detection of theforward target using the first detection signal and the second detectionsignal in an integrated manner is not continued, and the forward targetis associated with a control-target-vehicle setting history thatindicates that the forward target has been set as the control-targetvehicle.
 6. The control-target vehicle setting apparatus according toclaim 3, wherein: the setting control unit sets the forward target asthe control-target vehicle when at least either of a distance betweenthe forward target and an own vehicle being less than a distancethreshold and a time-to-collision regarding the forward target beingless than a determination threshold is determined when the forwardtarget is not associated with the integration history, detection of theforward target using the first detection signal and the second detectionsignal in an integrated manner is not continued, and the forward targetis associated with a control-target-vehicle setting history thatindicates that the forward target has been set as the control-targetvehicle.
 7. The control-target vehicle setting apparatus according toclaim 4, wherein: the setting control unit does not set the forwardtarget as the control-target vehicle when the forward target does nothave the integration history, detection of the forward target using thefirst detection signal and the second detection signal in an integratedmanner is not continued, and the forward target is not associated withthe control-target-vehicle setting history.
 8. The control-targetvehicle setting apparatus according to claim 1, wherein: the settingcontrol unit does not set the forward target as the control-targetvehicle when at least either of the forward target being associated withan oncoming vehicle history that indicates that the forward target hasbeen determined to be an oncoming vehicle and the forward target beingdetermined to be an upper object on the driving road is established,even when the forward target is associated with the movement history. 9.The control-target vehicle setting apparatus according to claim 2,wherein: the setting control unit does not set the forward target as thecontrol-target vehicle when at least either of the forward target beingassociated with an oncoming vehicle history that indicates that theforward target has been determined to be an oncoming vehicle and theforward target being determined to be an upper object on the drivingroad is established, even when the forward target is associated with themovement history.
 10. The control-target vehicle setting apparatusaccording to claim 3, wherein: the setting control unit does not set theforward target as the control-target vehicle when at least either of theforward target being associated with an oncoming vehicle history thatindicates that the forward target has been determined to be an oncomingvehicle and the forward target being determined to be an upper object onthe driving road is established, even when the forward target isassociated with the movement history.
 11. The control-target vehiclesetting apparatus according to claim 4, wherein: the setting controlunit does not set the forward target as the control-target vehicle whenat least either of the forward target being associated with an oncomingvehicle history that indicates that the forward target has beendetermined to be an oncoming vehicle and the forward target beingdetermined to be an upper object on the driving road is established,even when the forward target is associated with the movement history.12. A control-target vehicle setting system comprising: a control-targetvehicle setting apparatus that sets a control-target vehicle that servesas a target for driving assistance control, the control-target vehiclesetting apparatus comprising a detection signal acquiring unit thatacquires a first detection signal that indicates a target by an imageand a second detection signal that indicates a target by a reflectionpoint, and a setting control unit that sets an acquired forward targetas the control-target vehicle when the forward target is associated withan integration history that indicates that the forward target has beendetermined to be a vehicle using the first detection signal and thesecond detection signal in an integrated manner, even when the forwardtarget is not associated with a movement history that indicates that theforward target has been detected as being a moving object: a firstdetecting unit that outputs the first detection signal; and a seconddetecting unit that outputs the second detection signal.
 13. Thecontrol-target vehicle setting system according to claim 12, furthercomprising: a driving assistance control unit that performs aconstant-speed driving and inter-vehicle distance control process as thedriving assistance control based on the set control-target vehicle,wherein the driving assistance control unit maintains deceleration whenthe own vehicle is decelerating, suppresses acceleration when the ownvehicle is accelerating, or cancels the constant-speed driving andinter-vehicle distance control process, when the control-target vehiclefor which the constant-speed driving and inter-vehicle distance controlprocess is performed is changed from the control-target vehicle to anon-control-target vehicle.
 14. A control-target vehicle setting methodfor setting a control-target vehicle that serves as a target for drivingassistance control, the control-target vehicle setting methodcomprising: acquiring a first detection signal that indicates a targetby an image and a second detection signal that indicates a target by areflection point; and setting a forward target as the control-targetvehicle when the forward target is associated with an integrationhistory that indicates that the forward target has been determined to bea vehicle using the first detection signal and the second detectionsignal in an integrated manner, even when the forward target is notassociated with a movement history that indicates that the forwardtarget has been detected as being a moving object.
 15. A targetpreceding vehicle setting apparatus for setting a target precedingvehicle for driving assistance control of an own vehicle, the targetpreceding vehicle setting apparatus comprising: a detection signalacquiring unit that acquires a first detection signal that indicates aforward object by an image and a second detection signal that indicatesthe forward object by a reflection point; and a setting control unitthat sets the forward object as the target preceding vehicle when theforward object has been determined to be a vehicle based on the firstdetection signal and the second detection signal, even when the forwardobject is not associated with a movement history.